This application describes and claims certain improvements in the basic electrochemical cell disclosed in U.S. Pat. No. 3,791,871. The basic mechanism of operation of the cell described in the aforementioned patent is incorporated by reference in this application. Briefly, the cell utilizes an alkali metal anode highly reactive with water spaced from a cathode by an electrically insulating film which forms naturally on the anode in the presence of water. This thin film permits the cathode to be placed in direct contact with the anode. The anode and cathode are immersed in an aqueous electrolyte. In U.S. Pat. No. 4,057,675 the cathode is in the configuration of a metal screen and the electrochemical reaction which occurs at the cathode in aqueous solution is the evolution of hydrogen.